Fannie Mae has announced a national policy under which it will no longer immediately evict tenants from homes on which it forecloses. Under the policy, the mortgage giant will in effect become a landlord or property manager for many homes where there is a foreclosure. Renters often face a difficult situation when a property is foreclosed upon, and this move will help those in Fannie-backed properties by providing some breathing room while they figure out what to do next.